1. Field of the Invention
The present invention relates to a sewing machine which is operable to form a stitch on a curved work fabric by an upper and a lower thread through cooperation of a shuttle and a needle which is vertically reciprocally driven, and particularly to a sewing machine which is suitable to embroider a cylindrical work such as a side portion of a cap or a hat. The present invention also relates to a holder device which is operable to retain the work fabric to be sewn by the sewing machine.
2. Description of the Prior Art
Japanese Patent Publication No. 4-40467 discloses a sewing machine which includes a drive mechanism (a fabric support frame in the publication) moved within a horizontal plane in both X-axis and Y-axis directions which are perpendicular to each other. A cylindrical cap frame for mounting thereon a work fabric or a cap to be embroidered is rotatable around Y-axis and is movable along Y-axis. The cap frame includes a rotary ring rotatably driven by the drive mechanism and a retainer member which is detachably mounted on the rotary ring and which has a peripheral portion on which a side portion of the cap is set. An embroidery window is formed on the retainer member, so that a part of the rim of the cap to be embroidered is positioned at the window.
With the above sewing machine, in order to provide more broader area in the circumferential direction of the side portion to be embroidered, the cap frame itself may be rotated even one revolution by the drive mechanism. However, since the embroidery window is formed on the retainer member as described above, the side portion can be embroidered at only the area corresponding to the embroidery window.
Further, in order to rotate the cap frame, Japanese Patent Publication No. 4-40467 as described above includes a rack and pinion mechanism associated with the drive mechanism. Japanese Patent Publication No. 1-53384 or Japanese Laid-Open Patent Publication No. 60-162853 discloses a link mechanism associated with a drive mechanism. Such mechanisms to rotate the cap frame are not suited to cope with the embroidery operation of the work fabric over its entire circumferential surface. Thus, as the rotational angle of the cap increases, the amount of movement required for the drive mechanism becomes larger, so that the size of the embroidery machine as well as the size of the drive mechanism in the X axis direction increases. Particularly, in case of a multi-head embroidery machine having a plurality of sewing heads, a greater distance is required between two adjacent sewing heads, so that the size of the embroidery machine becomes more larger.
Additionally, in general, when a cap is mounted on a retainer member of a cap frame of an embroidery machine for an embroidery operation, a broader embroidery area is required for embroidering the entire circumferential surface of the side portion of the cap. However, the side portion is normally spread out toward an opening, so that the cap must be mounted on the retainer member such that the central axis of the side portion is inclined relative to the rotational axis of the cap frame so as to position a part of the side portion to be embroidered in parallel to the axial direction of the retainer member or in parallel to a throat plate. For this reason, the other part of the side portion extends excessively toward the retainer member, resulting in that the sewable area of the side portion is reduced at this part.
Japanese Laid-Open Patent Publication No. 2-251660 discloses an improvement in which an annular pressing member for pressing a cap on a retainer member has a middle portion protruding toward a visor portion of the cap so as to prevent a part of a side portion of the cap adjacent the visor portion from creasing when the side portion has been pressed on the retainer member by the pressing member. This may permit such a part of the side portion to be suitably embroidered.
With this construction, however, the problem of a narrowed sewable area is still caused with respect to the other part of the rim for the same reason as previously explained.